diff --git a/.changeset/claude-validation-followups.md b/.changeset/claude-validation-followups.md
new file mode 100644
index 000000000..a28238318
--- /dev/null
+++ b/.changeset/claude-validation-followups.md
@@ -0,0 +1,5 @@
+---
+"agent-bundle": patch
+---
+
+Resolve Claude plugin directories before invoking the host validator, and fail validation when the Claude CLI version probe cannot complete successfully.
diff --git a/packages/agent-bundle/src/host-contracts/claude-plugin-validation.ts b/packages/agent-bundle/src/host-contracts/claude-plugin-validation.ts
index 86149652f..db60988ce 100644
--- a/packages/agent-bundle/src/host-contracts/claude-plugin-validation.ts
+++ b/packages/agent-bundle/src/host-contracts/claude-plugin-validation.ts
@@ -1,4 +1,4 @@
-import { dirname } from 'node:path';
+import { dirname, resolve } from 'node:path';
 
 import type { Diagnostic, DiagnosticSeverity } from '../core/diagnostics.ts';
 import { freezeDiagnostics } from '../core/diagnostics.ts';
@@ -61,7 +61,9 @@ const diagnostic = (
   message,
   recovery: code === 'AB6019'
     ? 'Install Claude Code and ensure `claude` is on PATH, then rerun artifact validation.'
-    : 'Run `claude plugin validate <bundle-dir> --strict`, repair the reported Claude artifact, and rebuild.',
+    : code === 'AB6022'
+      ? 'Verify the Claude CLI starts and responds, then rerun `claude plugin validate <bundle-dir> --strict`.'
+      : 'Run `claude plugin validate <bundle-dir> --strict`, repair the reported Claude artifact, and rebuild.',
   severity,
   target,
 });
@@ -88,33 +90,49 @@ const issueLines = (output: string): readonly { readonly message: string; readon
 export const validateClaudePlugin = async (
   options: ValidateClaudePluginOptions,
 ): Promise<ClaudePluginValidationReport> => {
+  const pluginDirectory = resolve(options.pluginDirectory);
   const executable = options.executable ?? 'claude';
   const run = options.run ?? runClaudeCommand;
-  const cwd = dirname(options.pluginDirectory);
+  const cwd = dirname(pluginDirectory);
   let version: string | undefined;
   try {
     const probe = await run(Object.freeze({ args: Object.freeze(['--version']), cwd, executable }));
     if (probe.exitCode !== 0 || probe.termination !== undefined) {
       return Object.freeze({
         diagnostics: freezeDiagnostics([diagnostic(
-          'AB6019',
-          'The Claude CLI is unavailable for host artifact validation.',
-          'info',
+          'AB6022',
+          probe.termination === 'timed-out'
+            ? 'Claude CLI version probe timed out.'
+            : probe.termination === 'output-limit'
+              ? 'Claude CLI version probe exceeded its output limit.'
+              : `Claude CLI version probe exited with code ${probe.exitCode ?? 'unknown'}.`,
+          'error',
           options.target,
         )]),
         host: 'claude',
-        status: 'unavailable',
+        status: 'failed',
         target: options.target,
       });
     }
     version = versionFrom(`${probe.stdout}\n${probe.stderr}`);
   } catch (error) {
+    if (!isErrno(error, 'ENOENT')) {
+      return Object.freeze({
+        diagnostics: freezeDiagnostics([diagnostic(
+          'AB6022',
+          'Claude CLI version probe could not be started.',
+          'error',
+          options.target,
+        )]),
+        host: 'claude',
+        status: 'failed',
+        target: options.target,
+      });
+    }
     return Object.freeze({
       diagnostics: freezeDiagnostics([diagnostic(
         'AB6019',
-        isErrno(error, 'ENOENT')
-          ? 'The Claude CLI is not installed or is not on PATH; host artifact validation was skipped.'
-          : 'The Claude CLI could not be started; host artifact validation was skipped.',
+        'The Claude CLI is not installed or is not on PATH; host artifact validation was skipped.',
         'info',
         options.target,
       )]),
@@ -127,7 +145,7 @@ export const validateClaudePlugin = async (
   let result: ClaudePluginCommandResult;
   try {
     result = await run(Object.freeze({
-      args: Object.freeze(['plugin', 'validate', options.pluginDirectory, '--strict']),
+      args: Object.freeze(['plugin', 'validate', pluginDirectory, '--strict']),
       cwd,
       executable,
     }));
diff --git a/packages/agent-bundle/tests/claude-plugin-validation.test.ts b/packages/agent-bundle/tests/claude-plugin-validation.test.ts
index 15c156ddd..05590ae99 100644
--- a/packages/agent-bundle/tests/claude-plugin-validation.test.ts
+++ b/packages/agent-bundle/tests/claude-plugin-validation.test.ts
@@ -1,3 +1,5 @@
+import { dirname, resolve } from 'node:path';
+
 import { expect, it } from '@rstest/core';
 
 import {
@@ -44,6 +46,24 @@ it('runs the installed Claude validator without shell interpolation', async () =
   });
 });
 
+it('resolves a multi-segment relative plugin directory before invoking Claude', async () => {
+  const fixture = runWith({ exitCode: 0, stdout: '✔ Validation passed\n' });
+  const pluginDirectory = resolve('fixtures/plugin');
+  await validateClaudePlugin({
+    pluginDirectory: 'fixtures/plugin',
+    run: fixture.run,
+    target: 'claude',
+  });
+
+  expect(fixture.calls).toEqual([
+    expect.objectContaining({ args: ['--version'], cwd: dirname(pluginDirectory) }),
+    expect.objectContaining({
+      args: ['plugin', 'validate', pluginDirectory, '--strict'],
+      cwd: dirname(pluginDirectory),
+    }),
+  ]);
+});
+
 it('keeps host warnings as warnings unless framework strict mode is enabled', async () => {
   const output = [
     '⚠ Found 2 warnings:',
@@ -122,3 +142,89 @@ it('reports an honest informational skip when Claude is absent', async () => {
     target: 'claude',
   });
 });
+
+it('fails host validation when the Claude version probe times out', async () => {
+  const report = await validateClaudePlugin({
+    pluginDirectory: '/tmp/plugin',
+    run: async () => ({
+      exitCode: null,
+      signal: 'SIGTERM',
+      stderr: '',
+      stdout: '',
+      termination: 'timed-out',
+    }),
+    target: 'claude',
+  });
+
+  expect(report).toMatchObject({
+    diagnostics: [expect.objectContaining({
+      code: 'AB6022',
+      message: expect.stringContaining('version probe timed out'),
+      severity: 'error',
+    })],
+    status: 'failed',
+  });
+});
+
+it('fails host validation when the Claude version probe exits nonzero', async () => {
+  const report = await validateClaudePlugin({
+    pluginDirectory: '/tmp/plugin',
+    run: async () => ({
+      exitCode: 2,
+      signal: null,
+      stderr: 'version failed',
+      stdout: '',
+    }),
+    target: 'claude',
+  });
+
+  expect(report).toMatchObject({
+    diagnostics: [expect.objectContaining({
+      code: 'AB6022',
+      message: expect.stringContaining('version probe exited with code 2'),
+      severity: 'error',
+    })],
+    status: 'failed',
+  });
+});
+
+it('fails host validation when the Claude version probe exceeds its output limit', async () => {
+  const report = await validateClaudePlugin({
+    pluginDirectory: '/tmp/plugin',
+    run: async () => ({
+      exitCode: null,
+      signal: 'SIGTERM',
+      stderr: '',
+      stdout: '',
+      termination: 'output-limit',
+    }),
+    target: 'claude',
+  });
+
+  expect(report).toMatchObject({
+    diagnostics: [expect.objectContaining({
+      code: 'AB6022',
+      message: expect.stringContaining('version probe exceeded its output limit'),
+      severity: 'error',
+    })],
+    status: 'failed',
+  });
+});
+
+it('fails host validation when the Claude version probe cannot be spawned', async () => {
+  const denied = Object.assign(new Error('spawn claude EACCES'), { code: 'EACCES' });
+  const report = await validateClaudePlugin({
+    pluginDirectory: '/tmp/plugin',
+    run: async () => { throw denied; },
+    target: 'claude',
+  });
+
+  expect(report).toMatchObject({
+    diagnostics: [expect.objectContaining({
+      code: 'AB6022',
+      message: expect.stringContaining('version probe could not be started'),
+      severity: 'error',
+    })],
+    status: 'failed',
+  });
+});